I don't beleive you will be having any significant problem by applying the well-used methods for isolation and analysis of polycyclic hydrocarbons. We have quite a bit of experience and did not record any difficulties. See ôur papers with Guarriges and Budzinski in my researchgate list. Best  

Dear Siti, 

working with hydrocarbons is not very easy. Especially if you are encountered with mixtures (from different stable compounds). It is critical to know the boiling points of the compounds in the mixture .Compound with lower boiling points in mixtures, evaporate more easily and change the composition of your mixture . It is recommended to transport samples in sealed capsules.

regards

Peyman

Evaporative losses are not only dependent on the volatility of the analyte expressed as vapor pressure or boiling point. Evaporative losses also depend on the medium from which the analytes have to evaporate. PAHs are well dissolved in various solvents and also well retained in soil and sediment, which leads to (very) limited evaporation. However, if the PAHs are present in pure water, evaporative losses can be more significant and will then be governed by the Henry´s law constant rather than by the boiling point. 2 and 3 ringed PAHs have the highest Henry´s law constants and are thus most prone to evaporative losses. We are sometimes adding 20-50% of methanol to our water samples in order to poison the sample (minus biodegradation) and also reduce evaporative and sorptive losses.  You should also be aware that when PAHs are in the dissolved state, they can be very prone to photodegradation, and you should thus protect your water samples and solvent extracts against the exposure to light (especially daylight).